Sees man in resort as one (2,5)
I believe the answer is:
en masse
'as one' is the definition.
(both can mean as a group)
'sees man in resort' is the wordplay.
'in resort' is an anagram indicator.
'sees'+'man'='seesman'
'seesman' is an anagram of 'EN MASSE'.
(Other definitions for en masse that I've seen before include "As a body (Fr.)" , "All together - in France (2.5)" , "All together (Fr.)" , "Sees man (anag.)" , "Many as one" .)